Comment 2 for bug 1377009

StacktraceTop:
 __libc_message (do_abort=do_abort@entry=1, fmt=fmt@entry=0xb769d79c "*** Error in `%s': %s: 0x%s ***\n") at ../sysdeps/posix/libc_fatal.c:175
 malloc_printerr (action=<optimized out>, str=0xb769d890 "double free or corruption (!prev)", ptr=0x834f9f8) at malloc.c:4996
 _int_free (av=0xb76e2420 <main_arena>, p=<optimized out>, have_lock=0) at malloc.c:3840
 __GI___libc_free (mem=<optimized out>) at malloc.c:2946
 av_free (ptr=0x0) at /build/buildd/libav-11/libavutil/mem.c:194